I interpreted that line as analogous to normal Windows security.
As a general rule, a would-be hacker can't get to any of your on-device data, Recall included, without a local user giving them access.
So the intent of the statement is to say it's immune to anything else being hacked, like servers. Not to say they finally invented a completely hack-proof system... and only used it for this single program.
Physical access means physical access to experts and the general public. Not physical access, social engineering, supply chain exploit, or remote code execution. Saying Windows can't be hacked without physical access would be false too.
> So the intent of the statement is to say it's immune to anything else being hacked, like servers.
Anything else would include Windows Update and Microsoft accounts.
They said Recall snapshots were stored on the PC itself and not available to Microsoft. Adding a misleading description of Windows security did nothing but confuse people.